CRM production

The expiry date becomes a simple problem when the producer is sure to sell all his material in a period where the stability test can still be performed. An answer could be to reduce the size of the batch so that the market can absorb it within two or three years. This would be a situation similar to pharmaceutical production where frequency of production and size of batch are market driven. Unfortunately, CRM production is a costly business. In particular for many matrix CRMs the end-user population is limited. Having larger batches of CRMs allows a decrease in the cost per unit. Decreasing the batch size will increase the cost of the CRM for the end user. Such cost would become unacceptable for measurements performed in highly specialised fields with limited numbers of laboratories (e.g. toxins, dioxins etc). 

It was assumed that the production of most obvious CRMs (i.e. simple matrix CRMs for classical parameters that were already produced in the past) could be tackled by commercial companies. The role of the European Commission is felt to be necessary when the technological risks for CRM production are significant. The development of CRMs is not a normal market since it involves very specialised manufacturing procedures. No commercial company can afford to develop CRMs in support of many purposes. Quality is the key word commercial materials might not be of sufficient quality to respond to the demand. The EC should act where national initiatives cannot comply with the demand. Participants considered that reference materials should be certified at the EC level, not at the national level, and that commercial products should refer to primary (certified) materials. A scheme should be developed for the mutual acceptance of materials, e.g. establishing a kind of EC label of quality in this context, accreditation of RM producers should become mandatory. 

Accreditation is mainly concerned with routine tests or analysis. It includes the use of reference materials (e.g. LRMs or in-house RMs) for control charts which are hardly available on the market it is hence timely to start producing RMs for routine analysis in high quantities and at low cost for those measurements which have a major economic importance in relation to social and environmental implications as mentioned above, such a production should follow minimum quality requirements to avoid commercialisation and use of bad quality products which would only add to confusion. There is obviously a need to focus/consolidate technical expertise for CRM production in a few centres of excellence and actions should be stimulated to create a possible network of CRM producers which should be composed of practitioners , i.e. experts in both the production of CRMs and the respective analytical fields, so that questions arising from routine laboratories could be readily and practically responded to [44] while efforts made by metrological laboratories to create a system of metrology in chemistry are certainly important, these are far remote from the needs of routine laboratories which, however, carry out the vast majority of analytical work worldwide. Pragmatism should... 

One solution to the problem may be to reduce the demand for CRMs by making available secondary RMs, designed and produced according to the quality standards established and implemented today for CRM production and traceable to CRMs. Such materials might find a use in all kinds of day-to-day quality control procedures and similar measures. This solution may lower the cost of production however, this approach is not applicable to all situations (e.g. CRMs are still lacking in many instances and the traceability link of secondary RMs to CRMs is questionable). 

The effects of concentration and sample purity on the redox potentials of the Fen/Fein couple in heme have also been studied usually the midpoint potentials are much higher in concentrated solutions than in more dilute ones [Adler (1)]. Reduction of FemCl36 TPP with Cr11 salts leads to a 96% percent transfer of the radioactivity towards the Crm product which confirms the inner-sphere electron transfer across an Fe—Cl—Cr-bridge [Cohen (37)]. 

Using radioactive Cl- in (NH3)5CoraCl2 +, he demonstrated that even when Cl-was present in solution, electron transfer occurred via direct (inner-sphere) Cl-transfer, such that the radiolabeled Cl- remained coordinated to the (now) nonlabile Crm product. 

A recent development in CRM production is the attempt to establish the maximum period over which the material may be used, which is, however, difficult to set out experimentally. Establishing such time windows is actually meant to fix the time frame... 

GuidanL CRM Product Performance Report. Guidant Corporation. SL Paul, MN, 2006. 

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